An indexing device for selecting a telephone number that is to be automatically dialed out is disclosed in Japanese Patent Application No. 214997 which was published in 1985. That publication describes a purely mechanical indexer combined with an electronic arrangement for retrieving the selected telephone number. That mechanical indexer employs a housing having in it a quantity of index cards stacked one atop another. The housing has a hinged cover which flips open upon activation of an unlatching bar. A slidable indicator is attached to the cover and, in the conventional manner of such indexers, is movable to line up with alphabetic symbols on the cover. For example, to find a listing for someone whose name begins with an M, the cover is closed and the indicator is moved to line up with the letter M on the cover. When the cover flips open, the indicator lifts all the cards overlying the index card for the letter M so that the M index card and the listings on it can then be seen. As is customary, each index card has lines (or spaces) on which names or other identifying information can be listed. Stored in an electronic memory in the indexer are telephone number data pertaining to each listing on the index cards. The stored data corresponding to a selected listing is read out (i.e. retrieved) by an electronic retrieval arrangement employing a detector which generates a "card" signal that identifies the chosen card by detecting the position of the slidable indicator. The retrieval arrangement, in addition, has a selector keying arrangement by which a particular listing on the card is selected. Upon actuation of a selected key, a "line" signal is generated which in conjunction with the "card" signal designates the address in the memory at which the corresponding telephone number is stored. To dial out the telephone number corresponding to the selected listing, the information stored at the designated address is read out from the memory.
An improvement upon the indexer described in the cited Japanese publication is disclosed in U.S. patent application Ser. No. 35,896, filed Apr. 6, 1987 now abandoned. In that improvement, apparatus for detecting the position of the slidable indicator is situated below the cards at one edge of the cover. The slider carries a pressure member that rides upon and resiliently presses down upon a thin insulative strip having an electrically conductive film coated upon its lower surface. When the slider is lined up with an alphabetic symbol on the cover, the pressure member forces the film on the strip to electrically contact a pad disposed on a substrate situated below the stack of index cards. The insulative strip must have sufficient restoring force to break the electrical contact immediately after the passage of the pressure member. Consequently, it is necessary to employ a material for the insulative strip that has a strong restoring force and which is able to endure the wear imposed upon it by the riding upon its upper surface of the pressure member. An insulative strip having a weak restoring force can enable the conductive film to to remain in contact with the pad after the pressure member has passed by and thereby cause the generation of false positional signals that may be confused with the true positional signals. That need for a wear resistant insulative strip whose strong restoring force is not impaired with usage nor diminished as the strip ages with the passage of time is one of the principal problems associated with this type of index device.
In addition to that problem, indexing devices of this type conventionally have a separate latch release button for opening the cover. In that conventional arrangement, the slider, with the cover latched down, is moved to line up with the appropriate symbol on the cover and the cover is then flipped open by actuation of the release button. Consequently, two separate and distinct steps are required with this conventional arrangement.